Hugh Laurie, who starred as a curmudgeonly doctor in the TV series "House" from 2004 to 2012, started out as a comic. That may explain his claims about exercising: "I run six to eight miles a day, plus weights and aerobics in the lunch hour. I also lie a lot, which keeps me thin."

Everyone has their own way of dodging a workout. But at some point, you just have to admit that making sure you get deep-breathing, sweat-producing activity most days is essential if you want to protect against brain drain as you age.

That’s because smooth, well-oxygenated blood flow to the brain is essential for keeping your neurons firing and your observational powers, focus, and memory strong.

A new study in the Journal of Applied Physiology looked at the benefit of brisk walking and jogging for a full year on brain blood flow in a group of 60- to 80-year-olds. The participants went from working out for 20 to 30 minutes three days a week for 26 weeks to doing it five days a week for the next 26 weeks, and they increased intensity as they could.

The result was that the blood flow in their brains was less affected by arterial stiffening and restriction; and pulse pressure in the carotid artery was lower. That means they had a better chance of retaining their cognitive powers throughout their life.

Talk to your doctor about what's smart for you to do, and then get out there. Going with the flow will keep you in the know.